A lot of log files in Exchange Database folders

 I have Exchange 2010 server. Today Windows server backup took a long time completing "checking exchange database consistency check"  than usual although the backup is running currently after completing consistency check. So I checked two exchange mailbox database folders. In one/first database folder, I have 4,149  log files. In another/2nd database folder, I saw 17,161 log files.  Out of that,15,241 were created on 12/17/2017. Fyi, I began moving a mailbox on afternoon of 12/16/2017 from first database to 2nd database which was completed at the night of 12/18/17.

 Also I noticed that Windows Server Backup has not run since 12/17/2017 until today. I tried to start the backup manually, but failed, After rebooting server, it began backing up after long consistency check.

 Is it normal to have this many log files? Did the mailbox move create this many log files?
 Should I leave them alone or do something to purge them?

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yo_beeDirector of Information TechnologyCommented:
This is expected when a move happens.
Here is a link to MS Social Network highlighting the same question with a solution.


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Pushpakumara MahagamageVPCommented:
Schedule exchange server nightly  maintenance backup. Backup will purge log files.

worth to read following articles.


yo_beeDirector of Information TechnologyCommented:
Here is the snippet from the accepted solution.

Move Mailbox Operations
Moving mailboxes is a primary capacity factor for large mailbox deployments. Many large companies move a percentage of their users on a nightly or weekly basis to different databases, servers, or sites. If your organization does this, you may find it necessary to provide extra capacity to the log LUN to accommodate user migrations. Although the source server will log the record deletions, which are small, the target server must write all transferred data first to transaction logs. If you generate 10 GB of log files in one day, and keep a 3-day buffer of 30 GB, moving 50 2-GB mailboxes (100 GB) would fill your target log LUN and cause downtime. In cases such as these, you may have to allocate additional capacity for the log LUNs to accommodate your move mailbox practices.

Also I would not recommend running your backup at the same time you are doing a move.

What version of exchange?  With 2010 you can move live. This may help you schedule moves and backup times.
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sgleeAuthor Commented:
Thanks for the information.
I am currently running a backup and will check in the morning to see if any of these log files have been purged.
Run full Exchange backup and select clear logs (I am not sure what is your backup software, but they all have that option).
After the successfully completed full backup, you might find a gap between the logs date and the files from 12/17 could be still there. Cut those files and move them to another folder. Restart the server, and if there are no errors, then you can delete those files a few days later.
If your backup software is giving you a trouble than run windows backup and that will sort the issue with log files.
yo_beeDirector of Information TechnologyCommented:
Just some additional details about the backup Exchange and the purging of logs.  I am almost sure by default the logs are purged once there is a successful full or incremental backup.

sgleeAuthor Commented:
Windows Server backup that I started last night after rebooting the server was completed this morning.
Most of log files are gone now.
221 log files in the 1st mailbox folder and were dated 12/19 & 12/20
954 log files in the 2nd mailbox database folder also dated 12/19 & 12/20

" If you generate 10 GB of log files in one day, and keep a 3-day buffer of 30 GB, moving 50 2-GB mailboxes (100 GB) would fill your target log LUN and cause downtime." ---> You were correct. Since the backup has not been performed for a few days, hence the number of log files grew.
sgleeAuthor Commented:
Fyi, I run Exchange 2010.

Thank you all.
yo_beeDirector of Information TechnologyCommented:
Not backing up your Exchange system daily is a very bad practice as it is pretty much true for any other mission critical system.  

On a side note I would rethink your entire backup procedure.
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